Alternative Text
Describe what is important in your images so everyone can understand them.
Impact
Images, infographics, and data visualizations can be powerful tools for understanding information — especially for visual learners. But what about people who cannot see them?
Alternative text (or "alt text") is a short description of an image. It helps people who cannot see the image understand what it shows. Screen readers read it out loud, and Braille devices display it.
Alt text makes sure that everyone (e.g., students, faculty, staff, and visitors) can get the same information, no matter how they access your website.
But alt text is not just for people with disabilities. It is also helpful:
- when someone has a slow internet connection and images will not load
- when someone wants to hear the description instead of see it
- when someone needs additional guidance breaking down complex visual information
- when you want to bring people to your page based on certain keywords (i.e., search engine optimization)
- when you want artificial intelligence to generate more accurate results (e.g., identify objects)
Adding alt text is a small step that helps everyone, including you.
How to
Think of it like explaining an image to someone in a meeting or classroom. Just say what is important or the takeaways.
Decision Tree
To know how to best provide an alternative for an image, let us go through the decision tree:
What is the purpose of the image?
- Can the image be deleted without losing information?
- Does the image provide additional mood, connection, or understanding?
If it is purely decorative, then select the image in Cascade CMS (or another web editor) and check the box for "Decorative Image".
New information in the image?
- Is there text near the image that provides the same information?
- This can be in the form of paragraphs, lists, and tables of text – not images of text.
If the information is already nearby, then select the image in Cascade CMS (or another web editor) and check the box for "Decorative Image".
What type of information is provided?
- Action Images (like buttons or icons)
What to do: Use the Alt Text field to restate the action.
Example: If the image says "Submit," your alt text should be: "Submit". - Simple Images (like photos or illustrations)
What to do: Use the Alt Text field to describe the image briefly — aim for 155 characters or less.
Example: "Student smiling while studying at a library table." - Complex Images (like charts, graphs, or infographics)
What to do: Use the Alt Text field to give a short summary, and let users know where to find a longer description nearby (like in the surrounding text or a linked page).
Example: "Chart showing enrollment growth. Full description below."
Best practices
- Focus on what matters.
Only describe the parts of the image that are important for understanding the content. Skip decorative details. - Keep it short — or link to more.
If the image is complex, give a brief summary in the alt text and include a longer explanation in the body of the page or link to another page. - Skip phrases like "image of" or "picture of."
Screen readers already know it is an image, so you do not need to say it again. - Do not use the file name.
Names like "IMG_1234.jpg" do not help anyone understand the image. - Avoid repeating what is already on the page.
If the same information is in the body text, there is no need to duplicate it in the alt text. - Use proper spelling and punctuation.
Alt text is real content — treat it like any other writing. - Make each alt text unique.
Even if images look similar, their purpose might be different. Write alt text that fits the context.
Frequently asked questions
Additional guidance
You can learn more about providing good alternative text to an image through these accessibility guides: